Communications headsets are used in a wide range of applications. Many headsets utilize some form of a microphone boom with a microphone located at the distal end of the boom so that it may be placed closer to the user's mouth. In other headsets, the microphone is located on a short boom closer to the headset receiver to achieve a more discreet appearance for the wearer.
One type of microphone commonly used is a noise canceling microphone. Noise canceling microphones (also referred to as differential or pressure gradient microphones) have two sound ports: a front port and a rear port. The front and rear ports act together to cancel out undesired ambient or background noise which arrives from a different angle and originates much further from the microphone than the voice of the user. Sound waves that arrive at opposite sides of the microphone diaphragm in equal phase and amplitude do not induce diaphragm vibration. This condition is referred to as acoustic cancellation.
In headset applications, a microphone boot assembly is oriented such that sound waves emanating from the desired sound source (i.e., the user's mouth) reach the front face of the diaphragm earlier and with greater amplitude than they reach the rear face of the diaphragm. Thus, acoustic cancellation is minimized. In contrast, sound waves emanating from sound sources that are located far away and in other directions arrive at opposite sides of the diaphragm closer in phase and amplitude, resulting in greater acoustic cancellation. Therefore, the microphone is less sensitive to ambient noise than to the user's voice. This process is referred to as noise cancellation.
Noise canceling microphones are susceptible to wind noise by their nature. Wind noise is caused by turbulent airflow around the headset boom front and/or rear ports to the microphone. This airflow causes random pressure fluctuations in the cavities coupled to the microphone. The noise canceling microphone undesirably converts this energy into noise in the audio signal, resulting in wind noise.
In the prior art, attempts to reduce the effects of wind noise have used folding booms. In the absence of wind, the folding boom is retracted to provide a discreet appearance. In windy conditions, the folding boom is extended to improve the signal-to-noise ratio. However, the use of a folding boom may provide only limited reduction of wind noise effects, and may be aesthetically undesirable to some users.
Thus, there is a need for improved methods and systems for wind noise suppression in microphone booms.